Telephone installation



E. A. DRISCOLL TELEPHONE INSTALLATION Filed Sept. ll, 1924 March 9,192e'. 1,575,743

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j mvENToR fom/m A'. -H/s cou Byu/ ATTORNEY Patented Mar. 9, 1926.

EDWARD A. IDRISCOLL, OFNEW YORK, N. Y.

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Application led September 11, 1924. Serial No. 737,052.

To all whom t may concern:

Be it known that' I, EDWARD A. Dnrsconn, a citizen of the United States,and resident of New York city, in the county of New York and State ofNew York, have invented certain new and useful Improvements in TelephoneInstallations, of whichthe following is a full, clear, and concisedescription.

My invention relates to telephone installa- A tions, my special purposebeing to simplify the apparatus constituting each individual telephoneset, so as to reduce to a minimum the number of parts required; and toenable a single Contact, .and a single actuating lever for opening andclosing said contact, to control the telephone set. i

I have discovered that a telephone set of the kind ordinarily used, forinstance a subscribers hand set, can be readily controlled in the mannerjust mentioned so as to be capable of giving service of goodfquality,both as to receivingand transmitting, and yet may be made up of `arelatively small number of separate parts if the parts and theirconnections be suitably proportioned as to the relative ohmic resistanceofcertain of these parts and otherwise arranged in accordance with-myinvention.

I accomplish rthe beneficial results above mentioned by so arranging thevariouselectrical connections as` to practically split a short portionof the line into two portions in parallel with each other, one portioninclud* ing the primary winding in series with the transmitter, theother portion including the secondary winding in series with thereceiver, the last mentioned portion being preferably of higher ohmicresistance than the other portion mentioned.

I call attention to my Patent No 1,507,- 668, Sept. 9, 1924, upon atelephone installation.

Reference is made to the accompanying set-in this instance a hand set,suitable for testing.

Figure 2 is a diagram of the wiring. A casing 1s shown at 3 and has theform of u. small ox, mounted in any. convenient position, and made ofwood or metal as desired.

Mounted within this box are a pair of contact members 4 and 5, togetherconstituting a single contact, and an actuating lever 6 for opening andclosing this contact. The lever 6 is provided with a portion 7 formedinto a hook, and with a presser finger 8, the latter being of insulatingmaterial. A spring 9, mounted within the casing 3, engages the underside of lthe lever 6.

The casing 3 carries a pair of binding posts 10 and 11 connected withthe two contact members 4 and 5, and also carries another binding post12, used as hereinafter described. y

A pair of line wires are shown at 13, 14, and bridged across them is abell 15 and a condenser 16, these partsand their uses being of the kindwell known in this art.

A hand casing v17 carries the diiferentelements of a hand set, connectedas hereinafter described. The casing is provided with a suspension ring1S, by aid whereof the hand set as a unit may be hungupon the hookportion 7 of the actuating flever 6. llVith the hand casing thus hung upthe actuating lever 6 occupies its lowermost position; and the singlecontact, made up of the two contact member 4 and 5, is open. I/Vhen,however, the hand casing is taken off the hook portion 7 the contact isclosed, dueto action of the spring 9.

A watch case receiver 19 and a transmitter 20 are carried by the handset casing 17, and may each be of the usual or any desired construction.y A. step up induction coil 21, carried by the hand set casing, servesas a handle for the hand set casing and parts carried thereby, inaddition to performing tho lusual function of any induction coil.

The'core of the induction Vcoil appears at 22, the primary winding at 23and the secondary winding at 24, these parts being constructed in theusual or any desired manner, the primary winding comprising a few vturnsofl coarse wire, and the secondary winding having a much larger numberof turns of liner wire. Y

A. cord 25 is connected withthe binding post 11, and is joined to twowires 26 and 27, the Wire 26 leading to the primary winding 23, and theWire 27 leading to the rem ceiver 19. From the primary winding 25 a wire28 leads to the transmitter 20.

Connected with the post 12 is a cord 29, which is joined to wires 30 and31; the wire 30 leading to the transmitter 20, and the wire 31 beingconnected with the secondary winding 24. Frein this secondary winding awire 32 leads to the receiver 19.

The two cords 25 and 29 are united into the form of a single cord 33,'which extends into the casing 17 through an opening eye .34. used forthe purpose.

The ohmic resistance of the receiver 19, transmitter 20, primarT winding223 and secondary winding 24 may be chosen witlr in wide limits. Onetypical apportionment of the resistance of the parts just mentionedmight be as follows: for the receiver 19, seventy-tive ohms; for thetransmitter 29, fifty ohms; for the primary winding '23, three ohms; forthe secondary winding 241A, one hundred ohms. Thus the total resist anceof the transmitter and primary winding, considered as in series witheach other, is fifty-three ohms, and the total resistance of thesecondary winding and receiver, considered as in series` with eachother, is one hundred and seventy-five ohms. The ligures here given,though adapted to work well in practice on almost any ordinary telephoneline, are more or less arbitrary. It is a matter of engineering toapportion the resistances of the various parts mentioned, and theproblem is different with different conditions' encountered in practice.

Generally speaking, however, 1 prefer to have the aggregate resistanceof the transmitter and primary winding,'considered as in series witheach other, considerably lower than the total resistance of the receiverand secondary winding, considered as also in series with each other.

Referring to the diagram shown in Figure 2, it will be noted that thetwo cords and 29, connected respectively with the binding posts 11 and12 as indicated more particulary in Figure 1, are essentially parts ofthe line; and for purposes of the line, as used vfor talking, are inseries with each other. Such being the case, and the ohmic resistance ofthe transmitter and the primary winding being, as above described,considerably less than the ohmic resistance of the receiver andsecondary winding, it follows that the portion ef the line, from thecord 29 to the cord 25, is essentially divided into two portions inparallel with each other, one of these pertions being of lower ohmicresistance than the other, the path of lower ohmic resist ance includingthe transmitter and primary winding, the path of higher resistanceincluding the receiver and secondary winding.

The bell 15 and the condenser 16, bridged across the line as abovedescribed and as indicated in the drawing, are used in the conventionalmanner; the ringing of the bell taking place while the contact is open,or in other words while the actuating lever 6 is in its lower position.

llVhenever the hand casing is removed from the hook 7 of the actuatinglever G, the contact is closed and the line is in condition for talking.

Suppose, now that the operator is talking into the transmitter 20. Atalking circuit may be traced as follows: line wire 1st, post 12, cord29 to junction of wires 30 and 31; here the circuit divides, but owingto the high resistance of the secondary winding 24: and receiver 19,most of the current flows through the wire 30, transmitter 20, wire 2?,primary winding 23, wire 2G, cord 25, binding post 11, contact members 5and 4f, binding post 1'() and line wire 13 to central station, or teanother subscribei"s station as the case may be, through a source ofelectricity not shown, and back to line wire 11.

This circuit energizes the primary winding .3, and causes the saine, byinductive action upon the core 22,r to energize the secondary winding24. The secondary currents thus induced energize the entire line,considered as including the receiver 19.

Any tendency for the secondary currents to become short-circuitedthrough the transniitter 20 and the primary winding 23 appears to be, toa great 'extent at least, offset by a choking action of the primary'wind ing 23.

`It is probable also, that in so far as the secondary or talkingcurrents thus induced in the winding 24 are not neutralized by a chokingaction of the primary winding 23, as just described, and thereforesucceed in passing through and energizing this winding 23, they causethis winding to perform its normal function as a primary winding andthus to act inductively upon and energize the secondary winding 24, soas to generate currents therein and in so doing Yto conserve a portionVof the energy which would otherwise be'wasted by short circuiting.

1n any event, I find by trial that by talking into the transmitter 2Othe line is energized quite strongly by currents in which the currentvariations are apparently :is great as they would be in the absence ofany tendency toward short circuiting.

For purposes of incoming signals the tall; ing currents, under controlof a distant station, in passing through the cord 29 and variousintermediate partsto the cord 25, tend to divide as above described withreference to the currents under control of the transmitter 20; but forthe reasons already stated, the incoming currents pass mainly if notaltogether through the secondary winding 24- and receiver 19, ratherthan through the primary winding 23 and receiver 20, and

thus practically follow only one of the two paths presented.

The secondary or talking currents used for incoming signals, and thuscontrolled from a distant station, follow a circuit which may be tracelas follows: line wire 14, binding post 12 and cord 29 to junction ofwires 30 and 31; here the current tends to divide, but for reasonsalready described continues for the most part, if not practically in itsentirety, through wire 31, secondary winding 24, wire 32, receiver 19and wire 27 to wire 25, thence through binding post 11, contact members5 and 4, binding post 10, line wire 13 to some lother station, thencethrough source of electricity not shown, and backto line wire 14.

My invention can be employed on any ordinary line used for talkingpurposes and whether used with acentral energy system or with individualbatteriesat the respective stations.

I iind that in practice, with my invention used upon a telephone line ofthe type 'commonly employed in large cities, the transmission is clear,side tones are reduced to a minimum, relatively little electric energyis required for operation of the line, and many kinds of nondescriptvagrant sounds, otherwise actually or constructively developed by:

the receiver, are completely done away with.

My construction is relatively simple, the various mechanical partsrequired being reduced to a minimum number, and the various electricalconnections being .so arranged as to develop a high degree of efficiencyin the system as a whole.

Above all I find this system well adapted for reducing to a minimum thenumber of contacts and contact members required, the particularembodiment here shown and described having for the individual stationonly a single contact consisting of two contact members. Y

IVhile the induction coil is here shown as associated with a testing setand as incorporated in a handle, it is obvious that the induction coilcan be used with any set, and

placed in any convenient receptacle as inv the prior art. p

I do not limit myself to the precise mechauism shown as variations maybe made and a secondary winding, atelephone line including said contactand having two portions in parallel with each other and each in serieswith said contact, one of said portions including said primary winding,the other of said portions including said r ceiver and the secondarywinding of the induction coil, and a ringer bridged across the line,said ringerl and both portions of said telephone line being controllableby said contact.

2. In a telephone installation, the com-v bination of a telephone line,va contact for opening step up induction coil having a primary windingand a secondary winding; said receiver and the secondary winding of saidinduction coil being in seri-es with each other and with said contactand receiver, but in parallel with said primary winding with referenceto said contact, and a ringer bridged across theli'ne, said ringerand'said induction coil being controllable by said contact. Y

3. In a telephone installation, the combination of a telephone-line, acontact for opening and closing the same, a ringer bridged across saidtelephone line and controllable by the opening and closing of saidcontact, a receiver, a transmitter, and an induction coil having aprimary winding and a secondary winding; said transmitter and theprimary winding of said induction coil being y in series with each otherand with said contact, saidreceiver and the secondarywinding of saidinduction coil being also in series with eachother and withv saidcontact, but in parallel with said transmitter and with said primarywinding with reference to said contact.

' Signed at New York City, in the county of New York and State of NewYork, this 8th day of September, 1924. EDIARD A. DRISCOLL.

and closing the same, a receiver, a

